Devices and methods for reducing vehicle drag

ABSTRACT

In certain embodiments of the present disclosure, a vehicle trailer is described that further includes a shelf component. The shelf component is separate from the rain gutter component. The shelf component extends from the rear wall of the trailer and includes a sloped surface.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 12/791,302, which is a continuation-in-partapplication of U.S. patent application Ser. No. 12/775,095 filed on May6, 2010.

BACKGROUND

An ongoing effort to reduce drag in vehicular structures is of greatimportance as fuel economy becomes an increasingly large considerationin vehicular design. As the drag of a vehicle increases, the amount offuel needed to move the vehicle also increases due to the greater energyrequired to overcome the drag. For instance, it has been stated that fora vehicle traveling at 70 mph, about 65% of the total fuel consumptionof the vehicle's engine is used to overcome drag. Therefore, even asmall reduction in the drag experienced by a vehicle traveling athighway speeds can result in a significant improvement in fuel economy.

For instance, heavy-duty vehicles such as tractor-trailers (also knownas semi tractors, tractors, class 8 long haul trucks, transfer trucks,18-wheelers, semis, etc.) have a tall and wide box-shaped profile thatcreates a significant amount of drag compared to smaller vehicles on theroad. For instance, Table I lists common drag coefficients of roadvehicles.

TABLE I Type of Vehicle Drag Coefficient (Cd) Low Drag Production Car.26 Typical Sedan  .3-.35 Sport Utility Vehicle .4-.5 Pick-up Truck.4-.5 Conventional Class 8 long haul tractor trailers .59-.63

In the U.S., vehicles commonly used to move freight typically include atractor which powers the vehicle and a trailer which contains thefreight. Tractors usually have 3 axles, the front, or “steer”, axlehaving two wheels, and two rear, or “drive”, axles each having a pair ofwheels on each side. The most common configuration of this type oftractor has 10 wheels; however, in some cases the traditional pairs ofwheels and tires are replaced by single wides; also known as “supersingles”, or wide-base singles. Single wide tires and wheels reduce theweight of the semi-trailer and in some cases reduce the rollingresistance of the vehicle. Tractors equipped with single wides only havesix tires and wheels. Smaller tractors, having a single drive axle (for6 wheels in total) are often used to pull shorter trailers in tighturban environments. The tires, wheels, axles, drive shaft,differentials, and other wheel components also create drag.

Cargo trailers have a similarly tall and wide box-shaped profile thatcreates drag because the enclosed cargo space of a trailer is oftenrectangular in shape. The most common type of cargo trailer in the U.S.is a dry box van that is 53 feet long. Most common cargo trailerstypically have two “tandem” axles at the rear, each of which has a pairof wheels for 8 wheels on the trailer. Tires and wheels on trailers canalso be replaced with single wides, reducing the total number of tiresand wheels on the trailer from 8 to 4. Again, the tires, wheels, axles,and other wheel components create drag. A cargo trailer also typicallyincludes landing gear, which includes legs that the trailer rests uponwhen detached from a tractor. The landing gear can also create drag.

Certain devices are known in the art, such as trailer sideskirts,fairings, trailer end caps, boat tails, and the like, which attempt toaddress certain areas of drag on a vehicle. However, many of thesedevices have significant limitations in their ability to reduce drag ortheir ability to be easily integrated into fleet operations. As aresult, a comprehensive solution for improving drag on a vehicle isstill needed.

Thus, a need exists for devices that are designed to provide dragreduction for a vehicle trailer. Methods relating to the utilization ofsuch devices would also be beneficial. Retrofit kits for incorporatingsuch devices into vehicles would also be beneficial.

SUMMARY

In accordance with certain embodiments of the present disclosure, avehicle trailer is provided. The trailer includes a roof and a floorseparated from each other by a pair of walls that extend along thelength of the floor. The roof has a front edge and a rear edge to andthe walls have a height that extends from the floor to the front edge ofthe roof, the height being substantially the same along at least aportion of the length of the walls.

The vehicle trailer further comprises an apparatus for reducing the dragof the trailer through reduction in the size of the wake behind thetrailer, increasing the pressure in the wake, and reducing the drag ofthe wheel and suspension components underneath the trailer.

In accordance with certain embodiments of the present disclosure, theapparatus can include an aerodynamic rain gutter component having afront edge and rear edge which is positioned on the roof adjacent to therear edge of the roof such that the front edge of the rain guttercomponent contacts the roof and the rear edge of the rain guttercomponent does not contact the roof. The apparatus can further include apair of fairings configured to be positioned on opposite sides of atrailer in front of wheels on the bottom of a trailer, a pair offairings configured to be positioned on opposite sides of a trailerbehind the wheels on the bottom of a trailer, with both pairs offairings placed and shaped to direct the air smoothly around the wheelsand tires and through the center of the trailer. The apparatus can alsoinclude a ramp in front of the suspension components, aerodynamicallyshaped wings on the axles, and a rear diffuser, such componentsconfigured to direct air smoothly between the trailer suspension and theground. The directed high energy air from the apparatus results in areduced trailer base drag.

In still other embodiments of the present disclosure, a vehicle traileris provided. The vehicle trailer includes a roof and a floor separatedfrom each other by a pair of opposing walls that extend along the lengthof the floor. The roof, floor, and walls define a space accessible by atrailer door with each of the walls having a front edge and a rear edgeand having a height that extends from the floor to the roof. The heightis substantially the same along at least a portion of the length of thewalls. The vehicle trailer further includes a pair of side wall fairingshaving a leading edge and trailing edge. Each side wall fairing ispositioned on a different wall from the other adjacent to the rear edgesof each of the walls such that the leading edge of each side wallfairing contacts the wall and the trailing edge of each side wallfairing does not contact the wall. Each side wall fairing has an upwardincline and downward incline.

In yet other embodiments of the present disclosure, a vehicle trailer isdescribed. The trailer includes a roof and a floor separated from eachother by a pair of side walls and a rear wall. The pair of side wallsextend along the length of the floor. The roof has a front edge and arear edge. The side walls have a height that extends from the floor tothe front edge of the roof The height of the side walls is substantiallythe same along at least a portion of the length of the walls. Thetrailer further includes a rain gutter component having a front edge andrear edge, the rain gutter component being positioned on the roofadjacent to the rear edge of the roof such that the front edge of therain gutter component contacts the roof and the rear edge of the raingutter component does not contact the roof. The rain gutter componenthas an upward incline and downward incline such that the distancebetween the rear edge of the rain gutter component and the floor is lessthan the average height of the side walls. Additionally, the trailerfurther includes a shelf component. The shelf component is separate fromthe rain gutter component. The shelf component extends from the rearwall and includes a sloped surface.

Other features and aspects of the present disclosure are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure, including the best mode thereof,directed to one of ordinary skill in the art, is set forth moreparticularly in the remainder of the specification, which makesreference to the appended figures in which:

FIGS. 1A and 1B illustrate a conventional tractor-trailer combination;

FIG. 1C illustrates a drag assessment of a conventional trailer.

FIGS. 2A and 2B illustrate perspective views of a trailer in accordancewith certain embodiments of the present disclosure;

FIG. 3A illustrates a perspective view of a trailer in accordance withcertain embodiments of the present disclosure;

FIG. 3B illustrates a plan view of a rain gutter component in accordancewith certain aspects of the present disclosure;

FIGS. 4A and 4B illustrate perspective views of a trailer in accordancewith certain embodiments of the present disclosure;

FIG. 5A illustrates a low pressure wake that forms at the rear of aconventional trailer when being pulled at highway speed;

FIG. 5B illustrates reduction in drag by directing the incoming air flowbetween the trailer wheel assemblies and injecting the high velocity airstream into the trailer wake at the rear of the trailer in accordancewith certain embodiments of the present disclosure;

FIG. 6 illustrates the drag contributions from the trailer back,underside, sides, and top and illustrates the reduction in drag fromthese trailer systems as a result of equipping the trailer with thecomponents of the present disclosure;

FIGS. 7A and 7B illustrate perspective views of a trailer in accordancewith certain embodiments of the present disclosure;

FIGS. 8A and 8B illustrate reduction in drag in accordance with certainembodiments of the present disclosure;

FIG. 9A illustrates a perspective view of a trailer in accordance withcertain embodiments of the present disclosure;

FIG. 9B illustrates a closer view of the perspective view of a trailerin FIG. 9A in accordance with certain embodiments of the presentdisclosure; and

FIG. 9C illustrates a plan view of a rain gutter component and a shelfin accordance with certain aspects of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to various embodiments of thedisclosure, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the disclosure, notlimitation of the disclosure. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present disclosure without departing from the scope or spirit ofthe disclosure. For instance, features illustrated or described as partof one embodiment, can be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present disclosurecovers such modifications and variations as come within the scope of theappended claims and their equivalents.

The present disclosure is generally directed to devices and methods forreducing vehicle drag caused by vehicle trailers. In this regard, theterm vehicle can refer to any type of vehicle. In particular, however,the present disclosure specifically contemplates use with heavy trucks,such as tractors and trailers connected thereto. The present disclosureidentifies key areas in which modifications to conventional trailers canresult in great reductions in vehicle drag, which can translate intoimproved fuel economy, reduced emissions of carbon dioxide, as well asother improved efficiencies.

As used herein, drag (also referred to as air resistance or fluidresistance) refers to forces that oppose the relative motion of anobject through a fluid (a liquid or gas). Drag forces act in a directionopposite to the velocity of the vehicle. Unlike other resistive forcessuch as dry friction, which is nearly independent of velocity,aerodynamic drag forces are dependent on the square of the velocity. Fora solid object moving through a fluid, the drag is the component of thenet aerodynamic or hydrodynamic force acting opposite to the directionof the movement. Therefore drag opposes the motion of the object, and ina powered vehicle it is overcome by thrust provided by the enginethrough the vehicle's drive train.

Turning to FIGS. 1A and 1B, a conventional tractor with sleepercompartment 10 with trailer 12 is illustrated. FIG. 1A is a side view ofthe tractor 10 with trailer 12 and FIG. 1B illustrates the underside. Aconventional tractor with sleeper 10 is shown as opposed to cab overengine design, which is also contemplated as a type of vehicle that canbe used with the present disclosure. A standard 53 foot long dry box vantrailer is illustrated but trailers of any length are contemplated foruse with the present disclosure

Tractor 10 includes side mirrors 14, axles 16, drive shaft 18, andwheels 20. Tractor also includes air dam 22. Trailer 12 is joined tosemi-trailer truck 10 at coupling point 24 typically referred to as the5^(th) wheel. Trailer 12 includes an enclosed cargo space 26. Enclosedcargo space 26 is generally rectangular in shape. Trailer 12 alsoincludes landing gear 28, axles 16, wheels 20, and suspension 29.

As discussed previously, many of the above-described components createdrag during operation of the vehicle. FIG. 1C illustrates a dragassessment of a standard dry van trailer. The trailer back isresponsible for creating the largest amount of drag on the vehicle. Thisis due to a low pressure wake that forms at the rear of the trailer whenbeing pulled at highway speeds. The low pressure wake is formed becauseair behind the trailer is moving at a very low speed relative to thehighway speed of the traveling vehicle. This low pressure wake pulls thevehicle back, creating the significant drag force. FIG. 5A shows animage of a low pressure wake that has formed at the rear of aconventional trailer being pulled at 65 miles per hour. In addition tothe trailer back, the trailer underside and tires also create asignificant amount of drag as the air collides with the tires, axles,and other fixtures underneath the trailer. The top and side surfaces ofthe trailer also create drag, although the drag is a relatively smallamount compared to the back and underside/tires.

In accordance with the present disclosure, certain improvements aredescribed which can significantly reduce vehicle drag.

Referring to FIGS. 2A and 2B, perspective views of a trailer inaccordance with the present disclosure are illustrated. The illustratedtrailer 12 can be joined to a tractor (not shown).

Trailer 12 includes roof 30, two side walls 32, two edge walls 34, andfloor 36, which define a space 26 for transport of cargo. Roof 30includes a front edge 38 (oriented toward the front of the trailer),rear edge 40 (oriented toward the rear of the trailer), and two sideedges 42 (extending along the sides of the trailer). Each edge isgenerally straight. Side walls 32 separate roof 30 from floor 36 andextend along the length of floor 36. As shown in FIG. 2A, side walls 32have a height that is substantially uniform across the length of eachwall 32 except toward the rear edge 40 of trailer, where the height ofeach wall varies as described further herein. The height for a portionof each wall extends from floor 36 to the height of the front edge 38 ofroof 30 again, except toward the rear edge 40 of trailer, where, incertain embodiments, the height can increase and then decrease inconformity to the sloped surface of rain gutter component 44 (describedfurther below) adjacent thereto. Edge walls 34 face the front of thetrailer and rear of the trailer. Rear edge wall 34 can provide accessinto space 26 as will be described in more detail.

In accordance with the present disclosure, aerodynamic rain guttercomponent 44 is illustrated. Rain gutter component 44 can be positionedadjacent to rear edge 40 of roof 30, over the existing rain gutter onthe trailer and be configured so as to have a portion 44A that anglesaway from floor and a portion 44B that angles back towards floor topoints above and below the plane defined by the roof 30. Rain guttercomponent 44 has a curved, sloping surface. In certain embodiments, sidewalls of rain gutter component 44 similarly increase in height anddecrease in height in conformity with the slope, which results in aportion of each side wall 45 extending above the height of roof 30. Wheninstalled, rear edge 44C of rain gutter component has a lower distanceto the ground and/or floor 36 than front edge of roof 38 and/or the sidewalls 45 (if present) adjacent to rear edge except for the portion ofeach side wall (if present) immediately adjacent to rear edge 44C, suchportion (if present) having a substantially identical distance to groundand/or floor 36 with rear edge 44C. For instance, when the rain guttercomponent is installed, the distance between rear edge 44C and floor 36can be from about 100 inches to about 105 inches. The length of raingutter component 44 that is curved can vary. The length of rain guttercomponent 44 can be from about 16 inches to about 40 inches (bycomparison, in certain embodiments, the total length of roof 30 on astandard 53 foot dry van trailer can be about 636 inches). Similarly,width of rain gutter component 44 that is angled can vary. The width ofrain gutter component 44 is typically the same width as the trailer andcan be from about 100 inches to about 102 inches (by comparison, incertain embodiments, the width of roof 30 can also be from about 100inches to about 102 inches). The height of aerodynamic rain guttercomponent 44 from the trailer roof 30 is about 1 inch to about 3 inches.Portion 44A can be angled at an angle from about 5 degrees to about 15degrees, more particularly at an angle of about 9 degrees to about 11degrees and portion 44B can be angled at an angle from about 10 degreesto about 20 degrees, more particularly at an angle of about 12 degreesto about 16 degrees. In some embodiments, rain gutter component 44 issubstantially a curved panel. The thickness of such a rain guttercomponent 44 can be from about ⅛ inch to about ¼ inch.

In certain embodiments, additional flap 47 can extend from rear edge 44Cand rain gutter component 44 and can articulate between variousdifferent angles. For example, when installed, flap 47 continues thecurve shown in FIGS. 3A and 3B but can be co-planar with rear edge wall34 in a first mode, and then pivot into a second mode in which flap 47continues along the angle of portion 44B in the direction of the ground.It is contemplated that at times, access to space 26 results in flap 47being adjusted or flexed accordingly. For instance, flap 47 can be splitin two haves along the center to correspond with the doors that formrear edge wall 34. In such embodiments, flap 47 would be generally flushwith rear edge wall 34 when space 26 is being accessed by opening suchdoors. To provide needed flexibility, flap 47 can be made of flexiblematerial as would be understood by one of ordinary skill in the art. Forinstance, rubber or the like can be utilized for flap 47.

Flap 47 can have a length from about 6 inches to about 15 inches and awidth from about 100 inches to about 102 inches. Further, flap 47 canhave a thickness from about ⅛ inch to about ¼ inch.

Referring to FIGS. 3A and 3B, a flap 47 in accordance with the presentdisclosure is illustrated. In such embodiments, flap 47 extends beyondrear edge wall 34 such that the total length of roof 30 and flap 47 isgreater than the length of floor 36. For instance, flap 47 can extendfrom about 4 inches to about 10 inches past rear edge wall 34.

As discussed above, rear edge wall 34 can provide access into space 26as would be understood by one of ordinary skill in the art. One suchembodiment is illustrated in FIG. 2A. For example, if flap 47 is capableof articulating, rear edge wall 34 can include a component that canpermit adjustment across certain angles. In addition, rear edge wall 34can be a conventional sliding door or conventional swing doors as arefound on conventional trailers, with the size adjusted to accommodatethe rain gutter component 44 and/or flap 47.

In accordance with the present disclosure, certain other aspects aredescribed. For instance, fairings can reduce the drag of the trailer asa result of certain trailer components.

Turning again to FIG. 2B, another pair of fairings is illustrated. Thepair of components 58 is positioned in front of wheels 20 and/or wheelassemblies 20. In this regard, a wheel assembly includes any combinationof wheels, tires, axles, differentials, and other wheel-relatedstructure, such as struts, shocks, springs, control anus, brakecomponents, or the like. The components are configured to direct fluidflow between the pairs of wheels 20.

Referring to FIGS. 4A and 4B, each component 58 has a generallyparabolic shaped cross-section that is generally parallel to bottomsurface 36. For example, each component has a generally flat bottomsurface 59A and top surface 59B that are generally parallel to bottomsurface 36 with the bottom surface 59A and top surface 59B having agenerally straight edge 60 and a generally curved edge 61. The leadingportion 62 of component 58 is oriented toward the front of the trailer12 and the trailing portion 63 is oriented toward the rear of thetrailer 12 with the side portions 64 connecting the leading portion 62and trailing portion 63. The leading portion 62 is curved in conformitywith the parabolic shaped cross-section and curved edge 61. hi addition,the leading portion 62 is curved as it extends from the bottom surface59A to the top surface 59B thereof The trailing portion 63 curves inwardtowards the front of trailer 12 as it extends from bottom surface 59A totop surface 59B such that the trailing portion 63 is generallycomplimentary to the curve of one or more adjacent wheels 20.

Each component 58 can be generally identical and positioned, asdiscussed above, oriented on opposite sides of trailer in front of eachpair of wheels 20. Each component 58 can have a length from about 12inches to about 28 inches. In addition, each component can have a widthfrom about 16 inches to about 27 inches. Each component can have aheight from about 19 inches to about 42 inches. For instance, thelength, width, and height can be comparable to that of each pair ofwheels.

Turning again to FIG. 4A, sloped component 66 can be positioned in frontof wheel assemblies 58, with, in certain embodiments, at least a portionpositioned in between components 58. The sloped component 20 can haveone or more sloped surfaces 68 that slope from bottom surface 36 to agenerally flat surface 70. The leading portion 72 of sloped component isgenerally flush with bottom surface 36 of trailer with the surface 68 ofsloped component 66 sloping downward in the direction of the ground. Theangle of slope can be from about 15 degrees to about 33 degrees. Sideportions 76 of sloped component 66 are generally coplanar with trailerside walls 32.

Sloped component 66 can have a length from about 36 inches to about 114inches. In addition, sloped component 66 can have a width from about 30inches to about 68 inches. Sloped component 66 can have a height fromabout 16 inches to about 40 inches. For instance, the width can beconfigured so that at least a portion of sloped component 66 fits inbetween components 58.

Referring again to FIGS. 4A and 4B, sloped component 66 directs airflowunderneath one or more axle components 80, which may or may not beintegrally formed with sloped component 66. Axle component(s) 80 isconfigured to be placed over the axle 16 of trailer 12. Axlecomponent(s) 80 can be in the form of one or more axle wings that have acurved front portion 82 and a generally flat body 84. Axle component(s)80 can have a length from about 12 inches to about 36 inches. Inaddition, axle component(s) 80 can have a width from about 23 inches toabout 68 inches. Axle component(s) 80 can have a thickness from about ⅛inch to about ½ inch. For instance, the width can be configured so thatat least a portion of axle component(s) 80 fits in between wheels 20 ofone or both axles 16.

For instance, in certain embodiments, two axle component 80A and 80B canbe generally identical and positioned, as discussed above, oriented overthe axle of trailer in between each pair of wheels 20 such that slopedportion 82A of the rear axle component 80A is adjacent to the flat body84B of the forward axle component 80B.

Turning again to FIG. 4B, yet another pair of fairings is illustrated.The pair of rear components 90 is positioned in behind wheels 20 and/orwheel assemblies 20.

Referring to FIGS. 4A and 4B, each rear component 90 has a generallywedge shaped cross-section that is generally parallel to bottom surface36. For example, each component has a generally flat bottom surface 92Aand top surface 92B that are generally parallel to bottom surface 36with the bottom and top surfaces 92A and 92B having a generally straightedge 94 and a generally curved edge 96. The leading portion 98 of rearcomponent 90 is oriented toward the front of the trailer 12 and thetrailing portion 100 is oriented toward the rear of the trailer 12 withthe side portions 102 connecting the leading portion 98 and trailingportion 100. The leading portion 98 is curved generally complimentary tothe curve of one or more adjacent wheels 20. In addition, the leadingportion 98 is curved as it extends from the bottom surface 92A to thetop surface 92B thereof. The trailing portion 100 curves outward towardsthe rear of trailer 12 as it extends from bottom surface 92A to topsurface 92B.

Each rear component 90 can be generally identical and positioned, asdiscussed above, oriented on opposite sides of trailer in behind eachpair of wheels 20 such that they are in a mirror-image orientation. Eachrear component 90 can have a length from about 12 inches to about 30inches. In addition, each component can have a width from about 14inches to about 27 inches. Each component can have a height from about16 inches to about 36 inches. For instance, the length, width, andheight can be comparable to that of each pair of wheels.

As shown in FIGS. 2A and 2B, the present disclosure further includes adiffuser 110. The diffuser 110 can include an integrated bumper 112 orcan be placed around an existing bumper (as illustrated in FIG. 4B).Diffuser 110 can have a generally rectangular cross section and can bepositioned behind rear wheel assemblies 20 adjacent to the rear end oftrailer 12. The diffuser 110 can define a cut-out 111 of any suitableshape or size to enable the trailer to be positioned adjacent to aloading dock and/or attached to a loading dock. Diffuser 110 can includeone or more sloped surfaces 118 that slope from the center 114 towardsthe sides 116. The angle of slope can be from about 0 degrees to about26 degrees. As seen in FIG. 4B, diffuser 110 can be hollow and thediffuser can have an open face or can have a closed rear face making thediffuser a sealed cube like object.

Diffuser 110 can have a length from about 14 inches to about 98 inches.In addition, diffuser 110 can have a width from about 26 inches to about102 inches (the full width of the trailer). Diffuser 110 can have aheight from about 25 inches to about 42 inches. For instance, as withthe other components, the length, width, and height can be comparable tothat of each pair of wheels.

In certain embodiments of the present disclosure, one or more side wallfairing(s) 200 are illustrated. Referring to FIGS. 7A and 7B, side wallfairings 200 are illustrated adjacent to the intersections 202 betweenrear edge walls 34 and side walls 32. Side wall fairing 200 can bepositioned adjacent to such intersections 202, which form the side rearcorners of trailer 12. Side wall fairings 200 are configured so as tohave a portion 204A that angles away from side wall 32 and a portion204B that angles back towards side wall 32 to points above and below theplane defined by the side wall 32. Side wall fairing 200 has a curved,sloping surface. In certain embodiments, side walls 206 of side wallfairing 200 similarly increase in height and decrease in height inconformity with the slope, which results in a portion of each side wall206 extending away from side wall 32. When installed, rear edge 208 ofside wall fairing 200 extends beyond intersection 202 and extends beyondthe plane defined by side wall 32 while leading edge portion 210 of sidewall fairing 200 is above the plane defined by side wall 32. When theside wall fairing is installed, the distance that rear edge 208 extendsbeyond intersection 202 is from about 0 inches to about 10 inches. Thelength of side wall fairing 200 can vary. The length of side wallfairing 200 can be from about 16 inches to about 40 inches (bycomparison, in certain embodiments, the total length of side wall 32 ona standard 53 foot dry van trailer can be about 636 inches). Similarly,height of side wall fairing 200 can vary. The height of side wallfairing 200 can be similar to the height of side wall 32 and can be fromabout 36 inches to about 117 inches (by comparison, in certainembodiments, the height of side wall 32 can also be from about 117inches). Alternatively, side wall fairing 200 can be formed by two ormore separate components that are joined together when installed, inwhich case each component has a length and width that when combined withthe other component(s) results in a total length and/or widthcorresponding to that previously described. The depth of aerodynamicside wall fairing 200 extending outward from the trailer side wall 32 isabout 1 inch to about 3 inches. Portion 204A can be angled at an anglefrom about 5 degrees to about 15 degrees, more particularly at an angleof about 9 degrees to about 11 degrees and portion 204B can be angled atan angle from about 10 degrees to about 20 degrees, more particularly atan angle of about 12 degrees to about 16 degrees. In some embodiments,side wall fairing 200 is substantially a curved panel having a similarif not identical profile to rain gutter component 44 describedpreviously. The thickness of such a side wall fairing 200 can be fromabout ⅛ inch to about ½ inch.

In certain embodiments, rear edge 208 of side wall fairing 200 is partof a rear extension 212 that extends beyond intersection 202 defined byedge wall 34 and side wall 32. Rear extension 212 can have a length fromabout 6 inches to about 15 inches and a height from about 36 inches toabout 117 inches. Further, rear edge fairing can have a thickness fromabout ⅛ inch to about ½ inch. When installed, rear extension 212 can beattached to the trailer side wall 32 and any suitable portion of thetrailer rear end frame (comprising intersections 202 which are separatedfrom one another by roof rear edge 40 and the equivalent floor rearedge) rather than the doors that define rear edge wall 34. In stillother embodiments, rear extension can be integral with the previouslydescribed portions 204A and 204B. Rear extension is configured to notinterfere with the trailer door operation. For instance, in certainembodiments, side wall fairing 200, and more particularly rear extension212, can define one or more slots 214 so as to clear trailer door hingeswhen side wall fairing 200 is installed on a trailer. In this manner,side wall fairing 200 can provide aerodynamic improvements that areindependent of loading and trailer door operation. Similarly, inembodiments of the present disclosure in which side wall fairing 200 isutilized in conjunction with the previously described rain guttercomponent 44, side wall fairing is positioned and configured so as tonot make contact with rain gutter component 44.

In certain embodiments of the present disclosure, shelf component 300can be present. Referring to FIGS. 9A-9C, shelf 300 is separate fromrain gutter component 44 and extends outward from rear edge wall 34. Asdiscussed herein previously, rear edge wall 34 can be a conventionalsliding door or conventional swing doors as are found on conventionaltrailers. In embodiments in which the previously described rain guttercomponent 44 is present on a trailer with swing doors, the presentinventors have determined that the addition of shelf 300 can allow forreduced drag, without the necessity of flap 47. However, it should beunderstood that shelf 300 can be used with any type of door(s) and/orwith or without flap 47, depending on the particular configurationselected in accordance with the present disclosure.

Shelf 300 has a top surface 302 that includes a sloped surface 304 whichangles towards the ground. In addition, shelf 300 extends lengthwiseacross the width of trailer rear edge wall 34. Sloped surface can beangled at an angle of about 10 degrees to about 20 degrees, moreparticularly at an angle of about 12 degrees to about 16 degrees.Referring to FIG. 9B, sloped surface 304 can extend from generally flatsurface 306 which is generally parallel with roof 30. However, asillustrated in FIG. 9C, sloped surface 304 can be substantially all oftop surface 302. In certain embodiments, top surface 302 has a length offrom about 3 inches to about 15 inches and a width of from about 95inches to about 102 inches. In certain embodiments, top surface 302 hasa length of about 8 inches. The length of sloped surface 304 can vary.For instance, sloped surface 304 can have a length of from about 1 inchto about 15 inches. Similarly, generally flat surface 306 can have alength of from about 1 inch to about 15 inches.

Shelf 300 can also include a bottom surface 308 that is positionedunderneath top surface 302 as illustrated in FIGS. 9B and 9C and isjoined to top surface 302 by one or more linking components 310 (suchthat the shelf 300 defines hollow spaces 312) or is instead integralwith top surface 302 as a solid structure. Bottom surface 308 can haveidentical dimensions to top surface 302. In embodiments in which shelf300 includes hollow spaces 312, shelf 300 may or may not include one ormore sidewall(s) 314 joining the edges of top surface 302 and bottomsurface 308. Shelf 300 can have a wall thickness of about 0.01 inches toabout 0.5 inches. In certain embodiments, at least a portion of topsurface 302 can be substantially parallel with a portion of rain guttercomponent 44, such as portion 44B.

Referring again to FIG. 9A, shelf 300 is installed adjacent to raingutter component 44 near the upper portion of rear edge wall 34. Shelf300 is installed on rear edge wall 34 between 0 and about 25 inchesbeneath the rear edge of roof 40 of trailer (the height of rear edgewall on a standard 53 foot dry van trailer is typically about 117inches). Shelf 300 can be mounted directly to rear edge wall 34 withappropriate hardware as would be understood in the art. Shelf 300 canalso be joined to rear edge wall 34 with hinges and/or other fastenersso as to enable shelf 300 to fold down towards rear edge wall 34. Shelf300 can be split in two halves along the center to correspond with thedoors which form rear edge wall 34. If shelf 300 is installed in twopieces on trailers with swing doors then each top surface 302 has awidth of about 45 inches to about 52 inches. Each swing door istypically configured to open approximately 270 degrees outward so as tobe almost flush with each side wall 32 that is closest to such swingdoor. The ability for shelf 300 to be split and articulate betweenpositions enables such swing doors to open to substantially the sameposition as they would otherwise swing without shelf 300. Shelf 300 canbe formed from an elastomeric material, including but not limited to EPMrubber, EPDM rubber, silicone rubber, ethylene-vinyl acetate,thermoplastic elastomers, thermoplastic polyurethanes, polybutadiene,and nitrile rubbers, or combinations thereof, or any other suitablematerial as further described herein or as would be known to one ofordinary skill in the art.

In this manner, the devices of the present disclosure reduce drag in anumber of ways including:

1. Directly minimizing the drag associated with incoming air flowcolliding with the tires, axles, brakes, and other mechanisms under thetrailer body. The sloped component 66, front wheel assemblies 20, andaxle wings 80A and 80B act as fairings to move the incoming air aroundthe tires, axles, brakes and other mechanisms under the trailer body.Additionally, this collection of components keeps the incoming air fromseparating as the air flows past the mechanisms underneath the trailer.

2. Accelerating and compressing the incoming air flow as it travelsbetween the collection of components (66, 58, 80A, 80B, 90, 110), thewheels, and the ground. The components, the wheels, and the groundcreate a tunnel with a rectangular cross section in which the compressedand accelerated air flows and ultimately is injected below the lowpressure wake at the rear of the trailer as shown in FIG. 5B (whencompared to a conventional trailer as illustrated in FIG. 5A). At therear of the trailer, the diffuser 110 deflects the air flow toward theground at an angle from 3 degrees to 10 degrees as shown in FIG. 5B.Injecting the accelerated and compressed air below the low pressure wakepulls the wake down and reduces its size, the sum of which increases thepressure in the wake, thereby reducing the resulting drag.

3. Directing the attached high velocity incoming air flow from the topof the trailer to the rear of the trailer at a downward angle ofapproximately 12-15 degrees as shown in FIG. 5B. The aerodynamic raingutter component 44 and flap 47 keeps the air flow attached and directsthe air downward into the low pressure wake. Injecting this highvelocity air flow into the low pressure wake reduces the size of thewake and adds energy to it. This increases the pressure in the wake,thereby reducing the resulting drag. FIGS. 5A and 5B compare the flowfield at the rear of the trailer without the components of the presentdisclosure to the flow field of the same trailer that is equipped withthe components of the present disclosure. FIG. 6 illustrates the dragcontributions from the trailer back, underside, sides, and top andillustrates the reduction in drag from these trailer systems as a resultof equipping the trailer with the components of the present disclosure.

4. Aerodynamically shaped side fairings thin the trailer side boundarylayer by accelerating the local flow over the side fairing and thendirect the air flow around the trailer edge to reduce the size of thewake and increase the local pressure on the back of the trailer, whichsubstantially reduces trailer drag. FIGS. 8A and 8B illustrate that theside fairing components maintain air flow attachment and direct the airinward into the low pressure wake. Injecting this high velocity air flowinto the low pressure wake reduces the size of the wake and adds energyto it. This increases the pressure in the wake, thereby reducing theresulting drag.

It should be understood that while the present discussion and figuresdescribe a dual tire configuration, a single wide tire configuration isalso contemplated by the present disclosure. In such embodiments, thepresent disclosure can be modified as would be understood by one ofordinary skill in the art to achieve the improvements described herein.

All of the above-described elements can be formed from any suitablematerial as would be known and appreciated in the art. For instance,metals, plastics, or the like can be utilized. Unless otherwise stated,the elements can include a smooth outline to further reduce drag. Inaddition, it should be appreciated that any suitable mounting hardwareincluding common fasteners (such as nuts, bolts, or the like), latches,hooks, ties, adhesives, magnets, or the like, or any other conventionalsecuring methods as would be known in the art can be utilized inconnection with the present disclosure. Similarly, any safety featuresas would be required by the appropriate regulatory agencies are alsocontemplated to be included as part of one or more components of thepresent disclosure in a manner so as to not eliminate the net reductionin drag achieved by the devices described herein. For instance,referring to FIGS. 9A and 9C, required safety lights 400 can beincorporated into the rain gutter component 44 described herein.

It should be understood and appreciated that various combinations of theabove described subject matter are contemplated by the presentdisclosure. In other words, drag improvements can be achieved by usingonly one of the above-described embodiments, but drag generally improvesif more than one component is utilized. In addition, the teachings ofthe present disclosure can be incorporated into new vehicle and trailermanufacture/sale as well as retrofit kits for upgrading existingvehicles and trailers.

The following examples are meant to illustrate the disclosure describedherein and are not intended to limit the scope of this disclosure.

EXAMPLES

Aerodynamic drag associated with trailers, tractor-trailer systems, andcomponents of the present disclosure were all assessed using NASA'sFully Unstructured Navier-Stokes 3D (FUN 3D) Computational FluidDynamics (CFD) model described further at http://fun3d.larc.nasa.gov. Inaddition, the actual fuel savings associated with trailers,tractor-trailer systems, and components of the present disclosure weredemonstrated using the industry standard Society of AutomotiveEngineer's (SAE) long-haul fuel-consumption test J1321 protocol,incorporated by reference herein, in a series of tests at theContinental tire proving grounds in Uvalde, Tex. The long-haulfuel-consumption test provides a standardized test procedure forcomparing the in-service fuel consumption of a test vehicle operatingunder two different conditions relative to the consumption of a controlvehicle.

Results of computational fluid dynamics modeling and simulations and SAEJ1321 testing are provided in Table IIA. In particular, Table IIA showsthat a modem tractor trailer combination equipped with certain elementsand components described in the present disclosure has 10% less dragthan the same tractor trailer without such components. For a tractortrailer operating on the highway at 65 miles per hour, a 10% reductionin drag results in a 5.5% improvement in fuel efficiency.

As illustrated in Table IIB, the SAE J1321 protocol tests at theContinental tire proving grounds in Uvalde, Texas demonstrated 6.81%improvement in fuel efficiency at 65 mph.

TABLE IIA Tractor Trailer Equipped with Baseline certain componentsTractor of the present Percent Trailer disclosure Improvement Cd ascalculated by .592 .5328  10% NASA's FUN 3-D Computational FluidDynamics Model Highway fuel 6.25 miles per 6.587 miles per 5.4%efficiency at 65 gallon gallon miles per hour

TABLE IIB Demonstrated * 6.252 miles per 6.678 miles per 6.81% Highwayfuel gallon gallon efficiency at 65 mph Using SAE J1321 Protocol *Testat Continental Tire Proving Grounds in Uvalde, Texas, Apr.5^(th)-10^(th), 2010.

In the interests of brevity and conciseness, any ranges of values setforth in this specification are to be construed as written descriptionsupport for claims reciting any sub-ranges having endpoints which arewhole number values within the specified range in question. By way of ahypothetical illustrative example, a disclosure in this specification ofa range of 1-5 shall be considered to support claims to any of thefollowing sub-ranges: 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

These and other modifications and variations to the present disclosurecan be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present disclosure, which ismore particularly set forth in the appended claims. In addition, itshould be understood that aspects of the various embodiments can beinterchanged both in whole or in part. Furthermore, those of ordinaryskill in the art will appreciate that the foregoing description is byway of example only, and is not intended to limit the disclosure.

1. A vehicle trailer comprising: a roof and a floor separated from eachother by a pair of side walls and a rear wall, the pair of side wallsextending along the length of the floor, the roof having a front edgeand a rear edge, the side walls having a height that extends from thefloor to the front edge of the roof, the height being substantially thesame along at least a portion of the length of the walls; a rain guttercomponent having a front edge and rear edge, the rain gutter componentbeing positioned on the roof adjacent to the rear edge of the roof suchthat the front edge of the rain gutter component contacts the roof andthe rear edge of the rain gutter component does not contact the roof,the rain gutter component having an upward incline and downward inclinesuch that the distance between the rear edge of the rain guttercomponent and the floor is less than the average height of the sidewalls; and a shelf component, the shelf component being separate fromthe rain gutter component, the shelf component extending from the rearwall and comprising a sloped surface.
 2. The vehicle trailer of claim 1,wherein the shelf component is inclined downwardly at an angle fromabout 10 degrees to about 20 degrees.
 3. The vehicle trailer of claim 1,wherein the shelf component is inclined downwardly at an angle fromabout 12 degrees to about 16 degrees.
 4. The vehicle trailer of claim 2,wherein the shelf component is configured to movably articulate betweena range of different angles.
 5. The vehicle trailer of claim 1, whereinthe shelf component is divided into two halves.
 6. The vehicle trailerof claim 5, wherein the rear wall comprises two doors.
 7. The vehicletrailer of claim 6, wherein the two doors can swing open 270 degrees. 8.The vehicle trailer of claim 1, wherein the rain gutter component isinclined downwardly at an angle from about 10 degrees to about 20degrees.
 9. The vehicle trailer of claim 1, wherein the rain guttercomponent is inclined downwardly at an angle from about 12 degrees toabout 16 degrees.
 10. A kit for retrofitting an existing vehicletrailer, the existing vehicle trailer including a roof and a floorseparated from each other by a pair of side walls and a rear wall, thepair of side walls extending along the length of the roof and floor, theroof having a front edge and a rear edge, the side walls having a heightthat extends from the floor to the front edge of the roof, the heightbeing substantially the same along at least a portion of the length ofthe side walls, the kit comprising: a rain gutter component having afront edge and rear edge configured to be positioned on a portion ofroof adjacent to and including the rear edge of the roof, wherein therain gutter component is configured to include an upward incline and adownward incline such that the distance between the rear edge of therain gutter component and the floor is less than the average height ofthe side walls; and a shelf component, the shelf component beingseparate from the rain gutter component, the shelf component beingconfigured to extend from the rear wall and comprise a sloped surface.11. A method of retrofitting a vehicle trailer, the vehicle trailercomprising a roof and a floor separated from each other by a pair ofside walls and a rear wall, the pair of side walls extending along thelength of the roof and floor, the roof having a front edge and a rearedge, the side walls having a height that extends from the floor to thefront edge of the roof, the height being substantially the same along atleast a portion of the length of the side walls, the method comprising:installing a rain gutter component having a front edge and rear edge onthe roof of the trailer, the rain gutter component being positioned onthe roof adjacent to the rear edge of the roof such that the front edgecontacts the roof and the rear edge does not contact the roof, the raingutter component having an upward incline and downward incline such thatthe distance between the rear edge of the rain gutter component and thefloor is less than the average height of the side walls; and installinga shelf component on the rear wall of the trailer, the shelf componentbeing separate from the rain gutter component, the shelf componentextending from the rear wall and comprising a sloped surface.
 12. Themethod of claim 11, wherein the shelf component is divided into twohalves.
 13. The method of claim 11, wherein the rear wall comprises twodoors.
 14. A vehicle trailer comprising: a roof and a floor separatedfrom each other by a pair of side walls and a rear wall, the pair ofside walls extending along the length of the floor, the roof having afront edge and a rear edge, the side walls having a height that extendsfrom the floor to the front edge of the roof, the height beingsubstantially the same along at least a portion of the length of thewalls; a rain gutter component having a front edge and rear edge, therain gutter component being positioned on the roof adjacent to the rearedge of the roof such that the front edge of the rain gutter componentcontacts the roof and the rear edge of the rain gutter component doesnot contact the roof, the rain gutter component having an upward inclineand downward incline such that the distance between the rear edge of therain gutter component and the floor is less than the average height ofthe side walls; a shelf component, the shelf component being separatefrom the rain gutter component, the shelf component extending from therear wall and comprising a sloped surface; and a pair of side wallfairings having a leading edge and trailing edge, each side wall fairingbeing positioned on a different side wall from the other adjacent to therear edges of each of the side walls such that the leading edge of eachside wall fairing contacts the side wall and the trailing edge of eachside wall fairing does not contact the side wall, each side wall fairinghaving an upward incline and downward incline.
 15. The vehicle trailerof claim 14, wherein the shelf component, pair of side wall fairings andthe rain gutter component are inclined downwardly at an angle from about10 degrees to about 20 degrees.
 16. The vehicle trailer of claim 14,wherein the pair of shelf component, side wall fairings and the raingutter component are inclined downwardly at an angle from about 12degrees to about 16 degrees.
 17. The vehicle trailer of claim 14,wherein the shelf component is configured to movably articulate betweena range of different angles.
 18. The vehicle trailer of claim 14,wherein the shelf component is divided into two halves.
 19. The vehicletrailer of claim 14, wherein the rear wall comprises two doors.
 20. Thevehicle trailer of claim 14, wherein the two doors can swing open 270degrees.